Continuous spinning and stretching process of the production of polyamide-6 filaments

ABSTRACT

A stretched polyamide-6-filament consisting of a polyamide-6, having a monoclinic structure, a Cu-K -X-ray reflection width measured in the half height of the equator reflection - of at least 2.35* corresponding to an angular distance of the (200) and (020) reflex of 0.8* and an infra-red extinction ratio E833/E1075 of 13. The polyamide-6-filament is prepared by a continuous spinning and stretching process which comprises the following steps : (a) dressing the filaments spun from the polyamide-6 melt immediately after they have been cooled with a non-ionic, high temperature resistant dressing agent, (b) drawing off under transposition, (c) stretching the filaments over stretching rollers, and (d) winding up the stretched filaments under tension.

United States Patent [191 Kubitzker et al.

[ Nov. 5, 1974 1 1 CONTINUOUS SPINNING AND STRETCHING PROCESS OF THE PRODUCTION OF POLYAMIDE-6 F ILAMENTS [75] Inventors: Harry Kubitzker; Bela Von Falkai;

Alfred Reichle, all of Dormagen, Germany [63] Continuation of Ser. No. 4,350, Jan. 20, 1970, abandoned.

[30] Foreign Application Priority Data Jan, 28, 1969 Germany 1904234 [52] US. Cl..... 264/210 F, 264/290 N, 264/342 RE [51] Int. Cl. D01f 3/10 [58] Field of Search 264/210 F, 290 N, 290,

264/342 RE; 117/6, 7; 260/78 L; 28/713 [56] References Cited UNITED STATES PATENTS 3,386,967 6/1968 Twilley 260/78 L 3,388,104 6/1968 Crovatt 260/78 L 3,415,791 12/1968 Crovatt et a1, 260/78 L 3,433,008 3/1969 3,437,641 4/1969 3,441,642 4/1969. 3,446,734 5/1969 3,454,535 7/1969 3,471,605 10/1969 Matsui et a1. 264/168 3,477,899 11/1969 Kubitzek et a1 161/173 3,493,646 2/1970 Larkin etal. 264/342 RE 3,504,078 3/1970 Au 264/210 F 3,511,677 5/1970 Strohmaier et a1. 117/7 3,553,305 1/1971 Au 264/210 F 3,558,760 1/1971 Olson 264/171 3,561,201 3/1972 Brignac et a1. 264/342 RE Primaiy Examiner-Jay H. Woo Attorney, Agent, or FirmPlumley & Tyner [5 7] ABSTRACT A stretched polyamide-6-filament consisting of a polyamide-6, having a monoclinic structure, a Cu-K -X-ray reflection width measured in the half height of the equator reflection of at least 2.35 corresponding to an angular distance of the (200) and (020) reflex of 08 and an infra-red extinction ratio E /E of 13. The polyamide-6-filament is pre: pared by a continuous spinning and stretching process which comprises the following steps (a) dressing the filaments spun from the po1yamide-6 melt immediately after they have been cooled with a non-ionic, high temperature resistant dressing agent, (b) drawing off under transposition, (c) stretching the filaments over stretching rollers, and (d) winding up the stretched filaments under tension.

5 Claims, 1 Drawing Figure CONTINUOUS SPINNING AND STRETCIIING PROCESS OF THE PRODUCTION OF POLYAMIDE-6 FILAMENTS This application is a continuation of Ser. No. 4,350, filed Jan. 20, 1970, now abandoned.

The invention relates to a continuous spinning and stretching process for the production of polyamide-6 filaments in which the spun monoor multi-filaments are treated with a temperature resistant dressing after they have been cooled and are immediately stretched after they have been drawn off.

, When stretched orientated polyamide-6 filaments are produced by the conventional process, they are first wound on to a spinning spool and, after being exposed for some time to moisture in which they undergo preliminary crystallisation in the hexagonal y-modification, they are orientated by stretching. The stretching process at the same time induces in the filaments the a-monoclinic crystal modification, which is regarded as thermodynamically the most stable, and rise in the proportion of crystalline material from to 10 to 25 to 30 percent. 1

The structural modifications can be characterised by X-ray or infrared-analysis. The non-stable hexagonal y-modification shows a distinct 002-meridian and a 200-I020 equator-reflection in the Cu-K -X-ray spectrum and amorpheous bands (p.i. 1170,1075 and 974 cm) in the infra-red spectrum, (measured at a parallel fibre band with polarised light. The momclinicB and a modifications show a widened equator-reflection with the separated 200- and 020 X-ray bands and cristalline absorption bands (1027,960 and 833 cm) in the infra-red spectrum.

The production of polyamide filaments would be rendered more economical by a continuous spinning and stretching process, but this continuous process would aments are treated with a temperature resistant dressing immediately after they have been cooled and are then drawn off and then stretched to 2.5 to 5.5 times their length, using one or two hot rollers at 170 to 220C, after which the stretched filaments are immediately wound under a tension of 0.02 to 0.08 g/dtex.

The resulting polyamide-6 filament shows a Cu-K X-ray reflection width measured in the half height of equator reflection of at least 2.35 followed by the separated 200 to 020 X-ray bands in an angulardistance of 0.8-and an infra-red extinction ratio of Essa/ 1015 2 0.13, determined according to the basal lines method of infra-red spectrum analysis and the equation E= (2E+ E)3.

In application in textile technique (sharing and knitting) the filaments show less than 0.05 faults/10 m.

In contrast to both the known processes and to the accepted ideas about residence times, end breakage rate or conditioning before stretching, this simple process provides the properties of which are consistently better than those filaments whichhave been produced in batches. Furthermore, the process involves no loss in spinning capacity, no special measures are taken to ensure induction of precrystallisation and no additional residence times are needed. Monoand multifilaments produced according to the invention show the following improvements in properties compared with filaments produced by conventional, i.e. batchwise, processes as known by the following patents: Belgian Pat. Nos. 666 681, 646 636, French Pat. Nos. 1409952, 1 533 457 and US. Pat. No. 3,002,804:

increased breaking strength with the same elongation at break, increased dyeability (with acid dyes),

' transparency (water clear) of unpigmented compositions and lustre gloss of unpigmented or only slightly pigmented compositions, reduced shrinkage on boiling, a-monoclinic modification of maximum stability undergoing no further crystallisation on boiling in water, increased uniformity of filaments and reduced longitudinal swelling.

Any grid spinning heads and extruders used practically may be used for spinning polymide-6 filaments. These filaments are spun under substantially the usual condition for the various titres in an ordinary blowshaft where they are cooled by an air blast. Below the blow shaft, the filaments are treated with a dressing which can withstand a temperature of up to 220C at least for a short time and which does not produce any additional deposits on rollers heated to 220C. A dressing which is temperature resistant up to 200C may, for example, consist of an aqueous emulsion of non-ionic melting agents such as oleic acid triglyceride, a phosphoric acid ester and a non-ionic emulsifier. The amount of the dressing agent applied to the filament is in the range of between 0.4 to 0.8 percent by weight.

The dressed filaments are drawn off using a draw-off roller with transposition device such as a ceramic rod or auxiliary roller which are looped round once or several times. It is advantageous to use a fixed ceramic rod and one or two loops round rod and roller. The drawoff roller rotates at 200 to 1500 m/min which is the usual spinning velocity for the various titres. The filaments drawn off with the more slowly rotating draw-off roller are then carried by means of an injector nozzle at least four times round a stretching roller heated to to 220C with an auxiliary roller placed at a slight distance from the stretching roller. Alternatively, the filaments can be passed round two similar or different stretching rollers both heated to about the sametemperature, and rotating at a rate which is 2.5 to 5.5 times the draw-off velocity, which depends on titre and spinning velocity. The filaments which have been stretched in this way and orientated by a continuous process are wound on to a winding spool or laid off in a storage device. This continuous process operating without times of stay enables the filament to be wound on friction driven spools with a very good package development. In this particular embodiment of the process, in which the winding rate is usually about 1 to 5 percent below the stretching rate, the relaxation of filament due to stretching is anticipated to such an extent that the filament is rendered stable to heat to such an extent that inspite of its negative water balance it runs on to the spool with the necessary pretension for the buildup of a good package, and neither in an extremely dry nor in an extremely moist atmosphere will it undergo changes which would impair the build-up of package and subsequent processing.

An embodiment of the process of the invention is illustrated in the drawing.

The filaments 2 extruded from the spinning dies 1 are cooled in the blow-shaft 3 by a blast of air, collected by a guide 4 and guided so that they meet the dressing rollers 5 rotating in dressing vats tangentially before they are drawn off by the draw-roller 6 with auxiliary roller or ceramic rods 7, being looped once or several times round these rollers. The auxiliary roller may free-wheel or be driven. From the draw-off roller 6, the filaments are stretched between 6 and 80 by a pair of stretching rollers 8a and 8b which rotate 2.5 to 5 times faster than the draw-off roller and are heated to 170 to 220C or by an equally hot stretching roller 8a and an undriven unheated auxiliary roller 9, and by passing at least three times round the pairs 8a, 8b or 8a, 9 they are fixed by heat so that they run with a sufficient pretension for satisfactory build-up of the package on the winding spool 10 which rotates more slowly by 1 to 5 percent.

Polyamide-6 melts obtained from autoclave shavings or from fully continuously operating condensation plants or obtained directly by fully continuous melting can be worked up by the process of the invention to produce filaments of high quality. The customary air conditioning in the draw-off room (winding room) is not necessary.

The following examples illustrate more particularly the invention.

EXAMPLE 1 Polycaprolactam autoclave shavings pigmented with 1.2 percent by weight of T10 and having a relative so lution viscosity of 2.76 in 1 percent m-cresol solution are melted in a grid spinning plant and extruded at 280C through 9-aperture dies having an aperture diameter of 0.25 mm, cooled in a blow-shaft with an air blast at 22C, dressed with an aquous emulsion of oleic acid triglyceride, a phosphoric acid ester and a nonionic emulsifier, carried once round a draw-off roller rotating at 1,400 m/min with ceramic rod arranged-at a small distance from the roller, looped 5 times round a pair of stretching rollers rotating at 4000 m/min and heated to 205C, and conveyed to a friction driven winding spool which rotates 1.5 percent more slowly. The quantity of oil applied to the filaments should be between 0.4 and 0.8 percent. The stretching and winding apparatus is situated in a room which is air conditioned at 22C and 50 percent relative humidity. The extrusion of the melt is adjusted so that the 9-filament yarn running on to the winding spool has a titre of 50 dtex. Application of the yarn is carried out using an air injector nozzle. The spun zero twist threads can be warped directly from the spinning spools with a very low defect count and worked up into knitted samples.

which can be dyed without streakiness. They have the following technical properties:

Tensile strength 5,5 g/dtex Elongation at break 35% Angular distance of sharp CuK radiation interferences (200) and (020) 1.55 degrees Intensity ratio of (002) and (200) interferences 0.19 lma/ 1015 EXAMPLE 2 Polycaprolactam shavings obtained from a fully continuously operating condensating plant and containing 0.3 percent of Ti0 and 0.2 percent of constituents which can be extracted with methanol and having a relative solution viscosity of 2.8 in m-cresol are spun and dressed as in Example 1, but at an extrusion rate which is 25 percent less than in Example 1. The draw-off roller is adjusted to 1,000 m/min and the stretching roller which is heated to 210C is adjusted to 3,000 m/min. The thread is guided once round the draw-off roller and ceramic rod and 6 times round the stretching roller and the air mounted auxiliary roller which rotates at a slight distance from the stretching roller, and is wound on a friction driven winding spool rotating at a 1 percent lower rate. The stretching and winding room is not air conditioned. The finished threads have the same properties as the threads in Example 1. The properties of the thread are practically unchanged when hot dry air is used in the auxiliary roller. When these threads are worked up, again only very low defect counts of the order of less than 0.1 for 1 kg are registered.

Tensile strength 5,4 g/dtex Elongation at break 37% Angular distance of the (200) and (020) equator reflection 1,45 degrees Intensity ratio of (002) and (200) interferences 0,22 E ssa/ 1015 0,30

EXAMPLE 3 A polycaprolactam melt taken directly from a fully continuously operating condensation plant is spun from a 4-aperture die with apertures of 0.6 mm diameter at a total outflow rate from an extruder of 27 g/min. The melt is not pigmented. The mass has a relative solution viscosity of 3.1 in m-cresol and contains 2.5 percent of constituents which can be extracted with methanol. The temperature of the die is 290C. The four filaments are wetted with an anhydrous preparation based on fatty acid ester, fatty acid ethanolamide and non-ionic emulsifier, looped three times round the draw-off roller rotating at 254 m/min and auxiliary roller rotating with it, and stretched in the ratio of 1:45 by which they are looped 5 times. These filaments are wound using a winding apparatus which operates at a constant winding tension. The filaments are water-clear and glossy. Their tensile strength is 7.3 g/dtex at 24 percent elongation at break. Their relative loop and knot strengths are distinctly above 80 percent.

Angular distance of the (020) and (200) reflection 1,6 degrees Intensity ratio of (002) and (200) X-ray interferences 0,08

(5) is carried out using a heated pair of stretching rollers.

3. The process of claim 1, wherein the stretching step (5) is carried out using a heated stretching roller with auxillary roller.

4. The process of claim 1 in which step (4), drawing off, is conducted at a speed of 200 to 1500 m/min.

5. The process of claim 1 in which step (6), windingup, is conducted at 'a rate l-5 percent below the stretching rate, step (5).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATH-m NO. 3,845,532

DATE? November 5, 1974 INVEMYORiS') 1 Harry Kubitzek et al N 'ascertifiedthat error appears in the above-identified patent and that said Letters Patent are herehy corrected as shown below:

In The Title Of" should be ---For-.

Under Foreign Applicatian Priority Data, *l904234 shnuld be ---].904234-.3

The inventor's name Harry Kuloitzker should be -Harrv Kubitzelfi" I Signed and sealed this 27th day of 1975.

AtteS-t:

C. MARSHALL DANN Commissioner of Patents and Trademarks RUTH C HAS ON Attesting Officer; 

1. A CONTINUOUS PROCESS FOR THE PRODUCTION OF STRETCHED POLYAMIDE-6 FILAMENT CONSISTING OF THE SEQUENTIAL STEPS OF
 1. SPINNING POLYAMIDE-6 FILAMENT FROM A MELT;
 2. COOLING THE SPUN FILAMENT;
 2. cooling the spun filament;
 2. The process of claim 1, wherein the stretching step (5) is carried out using a heated pair of stretching rollers.
 3. The process of claim 1, wherein the stretching step (5) is carried out using a heated stretching roller with auxillary roller.
 3. dressing the filament immediately after cooling with 0.4 to 0.8 percent by weight of a non-ionic dressing agent which is temperature resistant up to 220*C;
 3. DRESSING THE FILAMENT IMMEDIATELY AFTER COOLING WITH 0.4 TO 0.8 PERCENT BY WEIGHT OF A NON-IONIC DRESSING AGENT WHICH IS TEMPERATURE RESISTANT UP TO 220*C;
 4. DRAWING OFF THE FILAMENT OVER A DRAW-OFF ROLLER WITH A TRANSPOSITION DEVICE;
 4. drawing off the filament over a draw-off roller with a transposition device;
 4. The process of claim 1 in which step (4), drawing off, is conducted at a speed of 200 to 1500 m/min.
 5. The process of claim 1 in which step (6), winding-up, is conducted at a rate 1-5 percent below the stretching rate, step (5).
 5. stretching the filament to 2.5 to 5.5 times its length using stretching rollers heated to 170* to 220*C; and
 5. STRETCHING THE FILAMENT TO 2.5 TO 5.5 TIMES ITS LENGTH USING STRETCHING ROLLERS HEATED TO 170* TO 220*C; AND
 6. WINDING UP THE STRETCHED FILAMENT UNDER A TENSION OF BETWEEN 0.02 TO 0.08 G/DTEX.
 6. winding up the stretched filament under a tension of between 0.02 to 0.08 g/dtex. 